Conventional semiconductor detectors of IR radiation typically require a significant volume of material to achieve a high quantum efficiency. This significant volume, while enhancing sensitivity to incident radiation, also serves to render the detector susceptible to optical attack and electromagnetic interference. Also, in semiconductor detectors, signal levels are detected as a change in a number of charge carriers excited across a gap characteristic of the semiconductor crystal lattice. This excitation results in a change in current or voltage across the detector. However, noise associated with a bias current (shot noise), reset voltage (thermal noise), or semiconductor defect distribution (1/f noise) limits the minimum signal levels that can be detected. High Temperature Superconducting (HTS) detectors typically require voltage bias, weak link structures and low level voltage amplification for proper operation.
HTS devices are generally comprised of a ceramic material that is inherently substantially immune to catastrophic damage by direct optical attack. For example, while operated in an oxygen atmosphere ceramic superconductors have been found to survive for significant periods of time at temperatures of 500-1000 C. Such ceramic superconducting detectors thus inherently provide for optical hardening. However superconducting detectors, due to weak link structures, have been found to be susceptible to magnetic flux interference at levels of a few gauss and also to electromagnetic interference which has been shown to cause steps in the I-V characteristics.
It is therefore one object of the invention to provide a HTS IR radiation detector that overcomes the problems associated with conventional semiconductor and HTS detectors while providing improved immunity to hostile nuclear and optical radiation, electromagnetic interference and high temperature environments.
It is another object of the invention to provide a HTS radiation detector that provides other advantages over conventional semiconductor and HTS detectors including an increased manufacturing yield, a larger size array, a reliable interface to readout electronics, a high sensitivity at longer wavelengths and a larger dynamic range.